Process of burning cement.



PATENTED AUG. l5, 1905.

B. E. ELDRED. PROCESS 0F BURNING CEMENT.

APPLICATION FILED APR. 8. 1905.

2 SHEETS-SHEET l.

PATENTED AUG. 15, 1905.

B. E. ELDRED.

PROCESS 0E BURNING CEMENT.

APPLICATION FILED APR. 8.1905.

2 SHEETS-SHEET Z.

BYRON E. ELllltltD, OF BRONXVlLL, NEW YORK, ASSlGrNOR TO ELDRED PROCESS COMPANY, OF NEW YORK, N. A CORPORATION OF NEW YORK.

lilo. 797.506

Specification of Letters Patent.

Patented Aug. 15, 190%.

Application tiled -April 8,*1905. Serial No. 254,474.

To all-1,077,077?, tm/ty concern.-

Be it known that` l, BYRON E. ELDRED, a citizen of the United States, residing at lronxville, in the county of Westchester and State of New York, have invented certain new and useful Improvements in Processes of Burning Cement, of which the followingspeciiieation and accompanying drawings illustrate thc invention in a form which il now regard as the best out of the various forms in which it may be embodied.

rlhis invention relates to the making' of Portland cement, which in the best modern practice is burned in rotary inclined or barrel kilns by means of a blast-flame of powdered coal projected from, one end of the barrel in heating relation to a continuous stream of the material fed along the ioor of the barrel. These instrumentalities l am able to utilize in a new manner and with improved results in respect to the consumption of fuel, the quality of the product, and the durability ofthe apparatus.

The powdered-fuel blast has hitherto `been used with certain objectionable limitations due principally to the extremely high temperatures attained and the diliculty of regulating the combustion. Thus, although this method has the advantage of affording a strong' Haine at a long distance from the root of combustion, it is also attended with the disadvantages, among others, of overheating, rapid deterioration of linings, inl'lexibility,l and waste of fuel. In burning lcement in rotary kilns with the powdered-coal blast it has become customary to employ a non-impinging axial flame, which is preserved from extensive contact with the material and lining by a stratum or envelop of air, an expedient which has the eifcct. of protecting the lining and material tosome extent from the intense heat of the iiame, but which results in quite a wasteA as products of combustion in the blast-eurrcnt, which modifies the flame and reduces its ,temperatur-e, rendering it longer, more slowburning and voluminous. Such a flame is found to be h'ot enough to calcme the lime .1n the cement-forming material and cool enough to be allowed to impinge directly on the lining and the material without undue injurious effeet upon either.

l prefer to separate the calcining and sintering operations and to malte the former precede the latter in point of space-that is, 1 may so regulate and graduate the temperature as as to perform practically all of the calcinlng in one portion of a traveling stream of matcrlal and practically all of the sintering'- in another portion. By so domga better product .is obtained and much fuel saved, since the calvdone with a comparatively low temperature-- that is, lower than the ordinary powdered-fuel blast-ilamc-whlle the sintering requires a high temperature, but may be done in a eomparatively short time and restricted space. rlihe separation of the calcining and sintering operations and their performance distinct successive stepsI believe to be new with me by whatever specific heating agents performed. I also believe the use of the specific agents described for burning cement to be broadly new. Heretofore the flame which has done the sintering has been used for calciningrbut as the sintering requires a higher temperaturc than the calcining and the single temperature heretofore used has had to be high enough to make fusion clinkers it follows that the'tcmperature has been unnecessarily high for calci'ning and fuel waste has occurred. The nature of the fiame heretofore used has not been suited to the most economical Work in this line.

There may of course in the practice of my .invention occur conditions under whicha of theproceedinghereindescribed.. ln employing blast combustion l may therefore producean inflated blast-flame, use the relatively cool diffuse portion thereof-for calcining or deearbonizing the lime in the cement material,

and locally intensify a portion of the fiame or a portion of the blast-current in order to produce a higher sintcring temperature. A

gaseous jet or jets, which may be a gas containing'free oxygen, preferably at a high pressure and directed at an angle to the blast-axis near the-root of the flame, so as to agitate and deflect a portion of the blast, may be utilized for the local sintering temperatures. The employment for this purpose of a plurality of tempera-tures independently controlled is an important feature of the invention.l he aux- -iliary jet being preferably directed upon a part of the kiln covered by cement material, the lining underneath is preserved from rapid burning out. y

I believe it to be new to calcinefthe cement material with a-flame produced as described. Having more or less separated the calcining step from the sintering step, I may of course omit the function of the intensifying-jet and reserve sintering or at least the final production of a hard clinker for a subsequent operation, though I prefer to use the high and low temperatures in cooperation for the completion of the burning of cement clinkers in one continuous series of steps.

The described method, per se, of producing and industrially applying a novel heating agent is not broadly claimed herein, being made the subject of a separate application.

For the performance of the process here set forth and claimed I have devised a certain novel combination of apparatus whereby the forces and materials concerned in the process are caused to coperate in the relation necessary to its exercise, which apparatus is also claimed herein.

In the accompanying drawings, Figure 1 represents a side elevation of a cement-burning furnace equipped to carry out this invention. Fig. 2 represents an enlarged sectional view of one end of the furnace. Fig. 3 represents a View, partly in section and lpartly in elevation, of the blast-nozzle and connections. Fig. 4 represents an end View of said nozzle.

"The same references characters represent the'same parts in all the figures.,-

In the drawings, 1 is the inclined rotary barrel of -a so-called horizontal7 cement- .kiln similar tothe ordinary, although permissibly longer than usual. The barrel has a refractory lining 2, Fig. 2, and at its higher end is the stack 3. At this end also is a screw conveyer or feeder 4 for introducing the material. At the lower end is a removable head 5, supporting the blast-nozzle 6 and combined with a stationary outlet 7 for the burned- Iclinkers.

A suitable concentrated or highpowered fuel, such as powdered coal, is f ed to the nozzle 6, in this case by means of a screw conveyer 8, from a bin or other receptacle and is blown into the kiln' with a jet of gaseous uid delivered through a pipe 9,v entering the rear end of the nozzle-pipe or combining-tube. The nozzle Gais flattened at the laterally.

The pipe 9 leads from the chimney 3 and end, as shown at Fig. 4, to spread. the flame contains a fan-blower 10, which serves to draw/back a Small portion or modicum ofthe inert gases or products of substantially complete combustion and force them into the kiln in company with the powdered fuel in predetermined proportion and in company with a predetermined volume of air drawn into the pipe 9 on the suction side of the fan at the point 11, whereat .is an adjustable valve or damper for regulating the proportionfof air.

There is also a'damper 12 in the trunk 'of the v pipe for regulating the'proportionv of stack gases. This proportion `should bezaccurately adjusted and may be varied toproduce a longer or shorter flame. The kiln-gases contain apercentage of' carbon dioxid `from calcination lof the lime as Well as from combustion. This gas is an efficient Vdiluent and endothermic agent. The nitrogen also acts as a diluent. The proportion of the totalkilngases returned'dependssomewhat upon their with this pipe, furnishes a jet of compressed air through the nozzle, which serves to' divert a portion of the mixed current ofl powdered fuel, stack-gases, and air issuing from the main nozzle and direct this current upon the iioor of the barrel near its lower end,`thereby obtaining by agitation and addition of air a localized high temperature for sinterin'g the cement mixture. This auxiliary air may, if desired, be preheated by any suitable expedient, as .may also the main air-supply, and the intensity of the local temperature may be reduced by modifying the jet, as by products of combustion. 'The main portion of the ame whichis unaffected by this secondary jet develops within the main body of the barrel land is of a voluminous slow-burning character, very long, cooler than the usual.

powdered-fuel ame, and'well suited to the preliminary calcination or decarbonization of the lime in the material. It is .preferably caused to hug the bottom of the kiln to a large extent. Favorable conditions for the maintenance of ignition and complete combustion are'furnished by the refractory reverberative lining of the barrel and the heat-retentive or incandescng character of the material. Owing to the slow-burning character of the iame and the increased Volume of the blast, the flame may be projected to the necessary extent with a weaker blast-current than has heretofore rst/,see

been used. Tl do not restrict myself as to the particular method'of driving the blast.

By means of the auxiliary jet a temperature may easily be attained amounting to GOOO Fahrenheit or more in excess of that afforded by the main flame and ample to edect the proper fusion of the clinkers.

li preferto furnish in the blast all or the main part of the oxygen necessary to a complete combustion, and in such case the chimney-damper may be so regulated as to reduce the chimney-draft and minimize the leakage of other air into the kiln. Any air which may tend to leak in through the opening' 7 is prevented by the auxiliary jet from forming `a stratum or envelop for the main blast.

There results a blast of large volume and low velocity, producing a voluminous slow-burning dame which fills the cross-section of the kiln and develops much of its heat in substantial contact with the material and the revolving lining, where it is of maximum effect. Sincethe temperature ol the flame is red uced, it hasbut little destructive effect on the lining. At 17 in the base of the stack .l have shown a damper by the adjustment of which the region of effective combustion may easily be shifted longitudinally of the kiln. By opening this damper the fiarne is held back toward the clinker-discharge end ofthe barrel and by closing it the fiame is lengthened toward the stack.

What l claim as new, and desire to secure by Letters Patent, is-

1. Theherein-dcscribed process of burning cement which consists in producing in operative relation to the cement-forming material a region of relatively low-temperature combustion suited to the calcination of the material, and a distinct region of relatively hightemperature combustion suited to -the sintering thereof.

2. The herein-described process of burning cement which consists in producing in operative relation to the cement-forming material in successive portions of a stream of the materiaha region of relatively low-temperature combustion suited to the calcination ofthe mai terial.- and a distinct region of relatively hightemperature combustion suited to the sintering1 thereof.

3. '.l'lrocessA of burning Portland cement which consists in calcining the lime in the material with a slow-burning voluminous flame i so regulated as not to sinter the' material.

a. Process of burning cement by successive steps which consists in first calcining the material with a slow-burning flame artificially inflated with products of combustion added to thesupply-current of the fire,'and later sintering the material with a higher temperature.

5. The described method of preparing cenient material for clinkering which consists in driving off the gasifiable portions from material containing lime and fusible ingredients in proportions to make Portland cement, without substantially fusing said fusible ingredients. Y

6. The herein-described process of burning cement which consists in performing substantially the whole of the calcining of the material at one time and substantially the whole of the sintering of the calcined material at a different time.

7. The herein-described process of burning cement which consists in performing substantially the whole of' the calcinng and substantially the whole of the sintering of a stream of cement material as distinct steps in successive sections of said stream.

8. The herein-described process of burning cement which consists in producing a slowburning voluminous flame in operative relation to the cement-forming material, and l0- cally intensifying' the activity of said flame in a desired region.

Sl. The herein-described process of burning cement which consists in producing a slowburning voluminous flame in operative relation to the cemen t-forming material to calcinc the lime in said material, and locally intensifying the activity of said fi ame by a transverse jet of air directed toward the material to effect the final sintering.

l0. The herein-described process ofburning cement which consists in calcining the lime in thematerial with a slow-burning voluminous 'flame applied in a substantially unobstructed space, and sintering the material by the action of a dame-intensifying pressure-jet.

1l. The herein-described process of burning cement which consists in causing the cementformingmaterial to travel through the furnace, causing a slow-burning voluminous flame to travel in operative relation to and in the opposite direction tothe material, and producing a local intensified combustion in the vicinity of the root of the flame.

'12. Process of treating cement material which consists in decarbonizing the lime therein with a long, slow-burning flame produced by means of a blast of previously-unignited fuel in suspension together with air and a gaseous diluent. f

13. Process of making cement in a kiln or furnace which consists in calcining the material with an artilieially-infiated flame of retarded combustion produced by means of a blast of previously-unignited fuel together with air and a volume of" gaseous diluent equivalent to a modicum of the total waste kiln-gases.

la. Process of making cement which consists in calcining the material with a blastflame containing powdered coal in suspension together with air and products of combustion.

15. Process of burning cement material which consists in calcining the lime with an artificially inflated or retarded impinging blast-flame. f

16. Process of burning cement material Vwhich consists in calcining the samevin a reverberatve chamber with an impinging slowburning flame produced with a blast containing powdered coal in suspension together with air and gaseous products of combustion.

17. The process of applying a powdered-fuel blast-dame to the calcination of cement material in a rotating refractory-lined chamber, which consists in inating the 4iame with products of combustion introduced with the blast, and causing said flame to substantially fill the cross-section of the working chamber.

18. Process of burning cement which consists in applying thereto a blast-flame of previously-unignited fuel sufficiently hot to calcine the lime in the cement material but not hot enough to complete the sintering.

19. Process of making cement which consists in feeding the material in astream, and passing over the same a diuse slow-burning blast-dame of concentrated fuel in suspension,

' so regulated as to calcine the lime but not fuse to the clinker condition with a high-temperature heating agent.

21. Processof making cement which consists in feeding the material ina stream, passing over the same a difuse slow-burning blastflame of concentrated fuel in suspension, so regulated as to calcine the lime but not fuse the clinker, and producing an adjacent higher temperature which fuses the clinker.

22. Process of burning cement which consists in calcining the lime in the cement-forming material with a ame produced by means of a blast of previously-unignited fuel in suspension, together with air and products of combustion, and sintering the hot calcined material with an adjacent flame of higher temperature.

23. .Process of burning cement which consists in calcining the lime in the cement-forming material with a flame produced by means of a blast of previously-unignited fuel in suspension, together with air and a diluent, and localizing the combustion of a distinct portion of said blast with a gaseous jet to produce a sintering temperature.

24. Processof making cement which consists in calcining the lime inI the cement'material with a relatively cool ame produced with a blast of previously-unignited fuel, air and products of combustion, and producing a local sinterig temperature withan auxiliary gaseous jet acting on a portion of the blast and directed toward the material. 'i

25,. Process of making cement which consists in calcining the lime in the cement material with a relatively cool ame produced with combustion, and sintering the material with a local high temperature produced by acting on a partial section of said blast with a transverse jet of air at a higher pressure than that of the blast.

26. Process of sintering cement which consists in acting thereon with an impinging flame of fusing temperature containing powdered fuel in suspension together with an added volume of gaseous products of combustion, and driven against the material by means of a highpressure jet.

27. Process of making cement clinkers which consists in acting on calcined cementforming material with a blast-llame ofpowdered fuel and gaseousdiluent concentrated with a high-pressure jet of air.

28. Process of burning cement which consists in passing a stream of the material through a furnace, cal'cining the body of said stream with a blast-dame of previously-unignited fuel traveling oppositely to the material and so regulated as not to fuse the same, and producing a local fusing temperature near the exit of said material from the furnace.

29. Process of burning cement which consists in acting on a progressing streamv of cement material with a powdered-fuel blastflame traveling oppositely to the material and rendered slow-burning by dilution, so as to calcine the material, and acting on the calcined portion of the stream near its terminus with a local high temperature caused by intensifying a portion of the blast.

30. Acement-burningfurnacecomprisinga reverberative chamber having provision for advancing the material along its door or hearth, a seat of combustion or propagation of the ame, connections anterior to said seat for deriving a supply of diluent fixed gas for retarding combustion, an air-supply inlet for supporting combustion, so disposed as to operate under forced draft, and means for artiy,ficially propelling the-draft=current for the iame.

.31. Acement-burningfurnace comprisinga reverberative chamber having provision for advancing the material along its floor or hearth, a seat of combustion or propagation of the flame, a iiue for discharging the products of combustion, a return-conduit for products of combustion branching from said flue a blast of powdered fuel, air and products of tion side of the fan, and means for varying the relative proportions of air and products of propelling blast-current therethrough, a jetcombustion in the fan-current.

33. Acement-brunngfurnacecomprisinga rotary inclined combustion-chamber having at one end a stack and devices for supplying the chamber with cementmaterial, and at the other end a seat of combustion or propagation of the flame, and connections for supplying underforced draft through said seat air for supporting the combustion of the llame and a diluent gas for retarding said combustion.

34:. A cement-burningfurnace comprising a rotary inclined combustion-chamber through which the material is caused to travel, a seat of combustion at one end thereof, a conduit leading to said 4seat and having connection at its receiving end with a source of gaseous diluent, draft-accelerating means for said diluent and the air-supply, whereby a forcible flame-current is projected from said seat into the combustioli-chamber, and an air-supply inlet on the suction side of said means.

35. Apparatus for burning cement comprising 'a hearth for supporting the cement material, means to supply the material to said hearth, a seat of combustion arranged for the projectionof a llame over said hearth, means to supply powdered fuel anterior to said seat, means to supply and propel a blast-current to drivethe fuel, and connections for deriving a volume of neutral products of combustion as a component of said blast-current.

36. A cement-burning furnace comprisinga reverberative roofed combustion chamber having a hearth for supporting the cement material, a blast-nozzle directed thcreinto, fuel-feeding and air-supply connections to said nozzle, connections from a furnace for supplying products of combustion to thenozzle as an ingredient of the blast-current, and pressureblast-producing means.

37. Acement-burningfurnace com )risinga longreverberativecombustion-chamber Whose loor constitutes a hearth for the support of the materials, fuel jet devices at one end of said chamber directed longitudinally therethrough, connections for supplying' to said jet devices unignited fuel, air to support combustion, and a fixed diluent gas to retard combustion, and propelling means in said connections whereby the air and diluent gas act to drive the fuel.

38. Acement-burning furnace comprisinga hearth having provision for advancing' the cement material therealong, means to supply a flame current of entrained fuel over the hearth, and a jet-nozzle directed toward the hearth and commanding a portion only of said current.

39. Acement-burningfurnace comprisinga combustion-chamber to contain the cementl material under treatment, a blast-nozzle directed thereinto, means for feeding powdered fuel to said nozzle, means for supplying a nozzle commanding said blast-current and directed at an angle to the axis' of the blast-nozzle, and means for supplying pressure fluid to said jet-nozzle.

10. Apparatus for burning cement comprising a hearth havingl provision for feeding the mate rial thcrealong, a seat of com bustion from which a flame is projected over the hearth, means for supplying' air and a flame-retarding diluent to said seat, an auxiliary jet-nozzle commanding the dilute-fuel current, and means to supply pressure liuid to said nozzle.

lll. A cement-burning furnace com prising a reverberative chamber having provision for advancing' the material therethrough, means for projecting a substantially axial llame through said chamber, and a jet-nozzle directed at an angle to the chamber-axis toward the lioor of the chamber near the materialdischarging end.

42. A cement-burning furnace comprising' an inclined rotary combustion and materialfeeding' chamber having a stack at the higher end, blastdevices at the lowerend for forcibly projecting a fuel-carrying llame-current longitudinally of the chamber, and a iet-nozzle at the lower end commanding the llame-current and directed downwardly toward the Afloor of the chamber.

4-3. Process of treating incandescing substanceswhich consists in passing thereover a long inflated impinging flame produced with a blast of preexisting concentrated fuel together with a supporter of combustion and diluent products of combustion.

44C. lrocess of treating materials disposed in a layer on the hearth of a reverberative chamber, which consists in subjecting the same to a superincumbent flame produced. vby a blast containing previously-unignited fuel and a supporter of combustion and modified by diluent gaseous products of combustion.

45. Process of treating incandescing materials in a reverberative chamber which consists in subjecting' the same to a long slowburning flame produced with a blast of powdered coal in suspension together with air and a modicum of the gaseous products of combustion.

46. Process of heating incandescing materials disposed on the hearth of a reverberative chamber which consists in subjecting the materials to an impinging, sloweburning, diffuse llame, produced with a blast of powdered coal containing a volume of burned-out gases equivalent to a modicnm of the total gaseous products of combustion.

a7. Process of applying "heat to mineral solids or other materials on a hearth which consists in subjecting the same to a superincumbent long, voluminous, slow-burning and relatively cool flame produceddwith a blast of powdered coal and neutral products of combustion together With air, and intensifying the combustion of a portion of said blast in a restricted region with an auxiliary jet of air directed toward the materials.

48. A process of 'treating materials'vvhich' consists in feeding the same in a stream, subjecting one section of said stream to a relatively low temperature flame produced with a blast of previously-unignited fuel, and subjecting another sectionto a relatively higher temperature produced by a concentrating' jet. In testimony whereof I have hereunto set my hand, in the presence of two subscribing 

